An OLED device, as a newly emerging display device, has attracted more and more attentions due to its advantages such as excellent contrast, self-luminescence, wide viewing angle, being of a thin-type, rapid response and low power consumption. However, the performance of an OLED, particularly an electrode and an organic layer thereof, may be degraded due to oxygen and moisture from an ambient environment entering the OLED display device, and at this time, its service life may be seriously reduced. In the case that the electrode and the organic layer of the OLED are hermetically isolated from the ambient environment (i.e., in the case that they are packaged), it is able to remarkably increase the service life of the OLED.
However, it is very difficult to hermetically isolate the electrode and the organic layer of the OLED from the ambient environment. In the related art, the OLED is sealed between two substrates using a packaging structure, with a resistance to oxygen of 10−3 cm3/m2/day and a resistance to moisture of 10−6 g/m2/day. In addition, the packaging structure may be provided with a width as small as possible (e.g., 1 mm), so as to prevent a size of the OLED device from being adversely affected. Further, the packaging procedure may be performed at a temperature as low as possible, so as to prevent the electrode and the organic layer of the OLED from being adversely affected. During the packaging, usually a pixel at a distance of 1 to 2 mm from the packaging structure may be at a temperature not greater than 1000° C. In addition, the packaging structure may be made of an electrically insulating material, so that an electrical element (e.g., an external membrane electrode) may be inserted through the packaging structure and into the OLED.
Currently, such laser packaging techniques as laser scanning packaging, laser point heating packaging and matrix laser packaging are mainly adopted. The laser scanning packaging technique refers to projecting a laser beam onto a packaging material (frit) at a surface of the to-be-packaged OLED device, and moving the laser beam along a profile of the packaging material so as to fuse the packaging material and complete the entire packaging procedure. The laser point heating packaging technique refers to performing laser point packaging at different positions of the packaging material, so as to complete the entire packaging procedure.
In order to increase the absorption of the packaging material (the frit) to the laser beam, usually such a metal oxide as bismuth oxide or vanadium oxide needs to be added into the packaging material. However, the metal oxide may become black after being fused by the laser beam and then solidified, and it may be visible from the outside in the case that it is applied to a transparent display device or any other element such as a transparent light source. As a result, the appearance of the entire product will be adversely affected.